Nickel-cadmium (NiCd) batteries are known from the prior art. Because of the heavy metal cadmium that they contain, they are harmful to the environment and can essentially only be used for special applications such as, for example, emergency power supplies.
It is likely that because cadmium-based batteries will become less available, cadmium-free batteries will increasingly be used for special applications too. It is especially likely that cadmium-based batteries will be replaced by cadmium-free batteries. This is expensive, however, because in some circumstances peripheral devices such as charging devices and the like need to be replaced too.